A. Field of Invention
This invention pertains to the art of methods and apparatuses for locking a tire press. More specifically, the present invention pertains to the art of methods and apparatuses for locking a tire press wherein a cylinder mechanism is utilized to provide substantially equal tension in all locking rods such that the tolerances for the length of each of the lock rods is not as critical as in known locking devices.
B. Description of the Related Art
It is known in the art for tire presses to have a locking mechanism so that a tire mold is secure during a curing cycle. Current devices utilize lock rods which must be substantially identical in length. As such, the lengths must be very precise and is very critical. The dimension is very critical because when a tire press closes and locks, if any of the lock rods are slightly longer than another one, the shorter rod sees more forces and loads. This results in an uneven load distribution which results in uneven strains and stresses. This may eventually cause tire defects because upper and lower tire molds may no longer be parallel. Further, the lock rods need to be over designed to take into consideration the fact that some of the lock rods may encounter more loads than others.
In other known designs, tension is placed on the lock rods; however, the lock rods and the guide posts of the tire press are the same mechanism. In this case, guide posts that have a locking mechanism integrated therein encounter increased maintenance. This is because guide posts should only be used for guiding the upper and lower mold halves open and closed during curing cycles. When actual forces are placed on guide posts through a locking mechanism, forces may cause deflection in the guide posts over time. As such, guide posts need routine maintenance.
The present invention provides methods and apparatuses for locking a tire press, which has independent lock rods and guide posts, and does not require the lock rods to be exactly equal in length, and yet, provides equal tension and axial forces in all the lock rods when the tire press is closed and locked.